1. Field of the Invention
The present invention relates to an imaging device such as a digital camera, and particularly to a focusing screen replacement mechanism of the imaging device.
2. Description of the Related Art
In a viewing optical system of a single-lens reflex camera, an optical image that has passed through a photographic lens and has been reflected by a main mirror is formed on a focusing screen. Then this optical image further passes through a pentaprism, an eyepiece, a finder window, and so on to reach the eye of a viewer (user). The viewer visually recognizes such an optical image and thereby can check the composition and so on of the photographing.
There are needs to use various kinds of focusing screens as the above-described focusing screen. In particular, professional photographers and semiprofessional photographers (high amateurs) have a need to use appropriate one among various kinds of focusing screens according to the photographing condition and so on.
For example, there is a focusing screen different from normal focusing screens in the appearance of an optical image dependent on the degree of focusing. For this focusing screen, processing with roughness different from that of the normal focusing screens is performed for the ground-glass-like surface (mat surface) thereof so that an image may be sharply seen only when the focused state is obtained more accurately. This allows a viewer to find the focused state more clearly.
Furthermore, there is also a focusing screen into which lattice lines are carved. This focusing screen allows a viewer to decide the composition with reference to the lattice lines (grid) disposed in the visual field.
In order to allow such various focusing screens to be easily replaced, some imaging devices include a mechanism for attaching/detaching focusing screens (focusing screen replacement mechanism) (refer to e.g. Japanese Patent Laid-open No. 2001-174880 (hereinafter, Patent Document 1)).
As shown in FIG. 26, this focusing screen replacement mechanism is provided around a focusing screen 98. In particular, a locking member 99 and so on for focusing screen replacement operation is provided in the opening on the inner circumference side of an annular lens mount part (on the main body side).